1. Field of the invention:
The present invention relates to an apparatus for detecting and indicating the balance of a rotating body such as a grinding wheel, a spindle or the like in a machine tool such as a grinding machine by detecting and indicating the amount of off-center deviation of the rotating body.
2. Description of the Prior Art:
Some machine tools employed for machining workpieces have spindles supporting rotating tools for machining the workpieces. Should the rotating tool attached to the spindle be unbalanced or the pulley and gears in the machine tool for driving the spindle be unbalanced, the spindle would be rotated eccentrically or out of trueness, and the workpiece would not be machined with trueness in its bore or on its outer periphery. Where the machine tool of this type is used for machining the workpiece with high accuracy, it is necessary to detect the amount of an off-center deviation of the spindle and correct it into proper balance. Especially in grinding machines, the rotating tool or grinding wheel is required to be properly balanced for accurate grinding operation.
For adjusting the rotational balancing of a grinding wheel, it has been customary to attach the grinding wheel to a single shaft placed over two horizontal bars, detect the direction and speed of rolling movement of the grinding wheel as it rolls of its own accord for determining the position and amount of eccentricity of the grinding wheel, and correct the grinding wheel to balance the same properly based on the determined off-center position and amount. However, such a balance correcting process relies on the worker's skill and hence is not sufficiently efficient. The conventional balance correcting process is not concerned with the correction of any unbalance of the shaft by which the grinding wheel is supported. Therefore, even when the grinding wheel is properly balanced, it will be rotated out of balance if attached to an unbalanced shaft.